Carbonizing box or the like



Patented Jm s, 192s.

UNITED STATES PATENT OFFICE.

CHARLES ELLISON MAOQUIGG, OF FLUSHING, NEW'YOBK, ASSIGNOB 'IO ELECTRO 'METALLURGICAL COMPANY, OF NIAGARA FALLS, NEW

OF WEST VIRGINIA.

No' Drawing.

like, of which the following is a specification.

Thi invention relates to alloys for use in the manufacture of articles r ulred to resist corrosion and disintegration at high' temperatures. More particularly the invention consists ofthe addition of copper to alloys of chromium with metals of the iron group for use in the'connection mentioned.

Alloys of chromium with one or more of I the metals of the iron group, especially iron,

nickel and cobalt, are much used because of their resistance'to oxidation, COIIOSlOIl and structural distortion at high temperatures.

For some industrial purposes, not only are these qualities required, but the alloy must be capable also of withstandingcarbonizing influences without deterioration. After articles mad from alloys ofthe kind specified hav been used for a time in operations where a material portion of their surface is subjected to carbon or carbonizing gases at elevated temperatures, cracking-or spalling frequently occurs when the articles undergo the rapid temperature changes incident to commercial heat treatments. In this way they-are often rendered useless long before corrosion, scaling, andthe like have substan- 'tially impaired the alloy.

Such disintegrative effects are encountered particularly in carbonizing or cementation boxes, and it is the principal object of my invention to provide improved boxes of this type. It will be understood, however, that the invention is applicable in general to the manufacture of articles to be subjected to carbonizing conditions.

My investigations tend to show that the cracking and spalling 'of articles, formed from chromium-iron alloys and the-like, under the conditions referred to, may be dueto absorption of carbon by portions of the alloy article, or to the formation of metal car- "metals.

YORK, A CORPORATION CARBONIZING BOX OR THE LIKE.

Application filed November 21, 1921; Serial No. 516,867.

age of the article when it undergoes changesin temperature, to the internal stresses set up by differences in the coefficients of expanwithout substantially impairing the strength or corrosion-resisting properties of the alloy.

Copper is the preferred metal for efi'ecting these results. The addition of copper seems to produce a favorable effect on the resistance of the alloys to oxidation and corroison, and does not interfere with their machining or forging.

Even relatively small quantities of copper have a desirable protective action on chromium alloys subjected to carbonizing condi tions, but in general the best results are obtained by adding copper in themaximum amount which will alloy with the other composition of the alloy. It may be said, however, that for alloys containing 20% or more of chromium, the limit of solubility of copper'is of the order of magnitude of 5 to 7%. Copper may be added with advantage to any of the oxidation-resistant alloys of chromium with metals of the iron group when such alloys are to be used for the manufacture of carbonizing boxes-or other devices intended for use under conditions favoring carbon absorption.

I claim: 1. An article .of manufacture composed of an alloyfcomprising chromium and a metal of the iron group, in amounts adapted to form anoxidation-resisting composition,

and suflicient copperto render the composition resistant to carbonization.

2. Anarticle of manufacture ada ted to resist carbonization and composed 0 'an alloy comprising chromium and iron in amounts adapted to form an oxidation-resistant body and copper in amount approximating its maximum solubility in th alloy.

3. An article of manufacture adapted to This amount is a. function of the posed of an alloy comprising chromium and iron in amounts adapted to form an oxida- 1 tion-resisting body and copper in amount approximating its maximum solubility in the alloy.

In testimony whereof, I afiix my signature.

CHARLES E. MAoQUIGG. 

